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195 lines
4.8 KiB
195 lines
4.8 KiB
/*
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* linux/arch/m68k/atari/stmda.c
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*
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* Copyright (C) 1994 Roman Hodek
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*
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details.
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*/
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/* This file contains some function for controlling the access to the */
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/* ST-DMA chip that may be shared between devices. Currently we have: */
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/* TT: Floppy and ACSI bus */
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/* Falcon: Floppy and SCSI */
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/* */
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/* The controlling functions set up a wait queue for access to the */
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/* ST-DMA chip. Callers to stdma_lock() that cannot granted access are */
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/* put onto a queue and waked up later if the owner calls */
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/* stdma_release(). Additionally, the caller gives his interrupt */
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/* service routine to stdma_lock(). */
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/* */
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/* On the Falcon, the IDE bus uses just the ACSI/Floppy interrupt, but */
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/* not the ST-DMA chip itself. So falhd.c needs not to lock the */
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/* chip. The interrupt is routed to falhd.c if IDE is configured, the */
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/* model is a Falcon and the interrupt was caused by the HD controller */
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/* (can be determined by looking at its status register). */
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#include <linux/types.h>
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#include <linux/kdev_t.h>
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#include <linux/genhd.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/wait.h>
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#include <asm/atari_stdma.h>
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#include <asm/atariints.h>
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#include <asm/atarihw.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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static int stdma_locked; /* the semaphore */
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/* int func to be called */
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static irq_handler_t stdma_isr;
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static void *stdma_isr_data; /* data passed to isr */
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static DECLARE_WAIT_QUEUE_HEAD(stdma_wait); /* wait queue for ST-DMA */
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/***************************** Prototypes *****************************/
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static irqreturn_t stdma_int (int irq, void *dummy);
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/************************* End of Prototypes **************************/
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/*
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* Function: void stdma_lock( isrfunc isr, void *data )
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*
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* Purpose: Tries to get a lock on the ST-DMA chip that is used by more
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* then one device driver. Waits on stdma_wait until lock is free.
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* stdma_lock() may not be called from an interrupt! You have to
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* get the lock in your main routine and release it when your
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* request is finished.
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*
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* Inputs: A interrupt function that is called until the lock is
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* released.
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*
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* Returns: nothing
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*
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*/
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void stdma_lock(irq_handler_t handler, void *data)
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{
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unsigned long flags;
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local_irq_save(flags); /* protect lock */
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/* Since the DMA is used for file system purposes, we
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have to sleep uninterruptible (there may be locked
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buffers) */
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wait_event(stdma_wait, !stdma_locked);
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stdma_locked = 1;
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stdma_isr = handler;
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stdma_isr_data = data;
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local_irq_restore(flags);
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}
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/*
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* Function: void stdma_release( void )
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*
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* Purpose: Releases the lock on the ST-DMA chip.
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*
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* Inputs: none
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*
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* Returns: nothing
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*
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*/
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void stdma_release(void)
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{
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unsigned long flags;
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local_irq_save(flags);
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stdma_locked = 0;
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stdma_isr = NULL;
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stdma_isr_data = NULL;
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wake_up(&stdma_wait);
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local_irq_restore(flags);
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}
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/*
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* Function: int stdma_others_waiting( void )
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*
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* Purpose: Check if someone waits for the ST-DMA lock.
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*
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* Inputs: none
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*
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* Returns: 0 if no one is waiting, != 0 otherwise
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*
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*/
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int stdma_others_waiting(void)
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{
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return waitqueue_active(&stdma_wait);
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}
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/*
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* Function: int stdma_islocked( void )
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*
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* Purpose: Check if the ST-DMA is currently locked.
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* Note: Returned status is only valid if ints are disabled while calling and
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* as long as they remain disabled.
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* If called with ints enabled, status can change only from locked to
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* unlocked, because ints may not lock the ST-DMA.
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*
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* Inputs: none
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*
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* Returns: != 0 if locked, 0 otherwise
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*
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*/
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int stdma_islocked(void)
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{
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return stdma_locked;
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}
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/*
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* Function: void stdma_init( void )
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*
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* Purpose: Initialize the ST-DMA chip access controlling.
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* It sets up the interrupt and its service routine. The int is registered
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* as slow int, client devices have to live with that (no problem
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* currently).
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*
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* Inputs: none
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*
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* Return: nothing
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*
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*/
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void __init stdma_init(void)
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{
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stdma_isr = NULL;
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request_irq(IRQ_MFP_FDC, stdma_int, IRQ_TYPE_SLOW | IRQF_SHARED,
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"ST-DMA: floppy/ACSI/IDE/Falcon-SCSI", stdma_int);
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}
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/*
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* Function: void stdma_int()
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*
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* Purpose: The interrupt routine for the ST-DMA. It calls the isr
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* registered by stdma_lock().
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*
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*/
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static irqreturn_t stdma_int(int irq, void *dummy)
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{
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if (stdma_isr)
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(*stdma_isr)(irq, stdma_isr_data);
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return IRQ_HANDLED;
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}
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